From bc908458ff24e42cc0c1ad32df44481456737bdb Mon Sep 17 00:00:00 2001
From: ecoal95 <ecoal95@gmail.com>
Date: Tue, 28 Jul 2015 16:58:53 +0200
Subject: [PATCH] webgl: Make context creation fallible. Fixes #6806

---
 components/compositing/constellation.rs       | 17 +++++++++------
 components/msg/constellation_msg.rs           |  2 +-
 .../script/dom/webglrenderingcontext.rs       | 21 +++++++++++--------
 3 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/components/compositing/constellation.rs b/components/compositing/constellation.rs
index 695c6688e9a..cf00da98960 100644
--- a/components/compositing/constellation.rs
+++ b/components/compositing/constellation.rs
@@ -942,12 +942,17 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
             &mut self,
             size: &Size2D<i32>,
             attributes: GLContextAttributes,
-            response_sender: IpcSender<(IpcSender<CanvasMsg>, usize)>) {
-        let id = self.webgl_paint_tasks.len();
-        let (out_of_process_sender, in_process_sender) =
-            WebGLPaintTask::start(*size, attributes).unwrap();
-        self.webgl_paint_tasks.push(in_process_sender);
-        response_sender.send((out_of_process_sender, id)).unwrap()
+            response_sender: IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>) {
+        let response = match WebGLPaintTask::start(*size, attributes) {
+            Ok((out_of_process_sender, in_process_sender)) => {
+                let id = self.webgl_paint_tasks.len();
+                self.webgl_paint_tasks.push(in_process_sender);
+                Ok((out_of_process_sender, id))
+            },
+            Err(msg) => Err(msg.to_owned()),
+        };
+
+        response_sender.send(response).unwrap()
     }
 
     fn handle_webdriver_msg(&mut self, msg: WebDriverCommandMsg) {
diff --git a/components/msg/constellation_msg.rs b/components/msg/constellation_msg.rs
index fcd9afdf7f0..6a11c7eb729 100644
--- a/components/msg/constellation_msg.rs
+++ b/components/msg/constellation_msg.rs
@@ -266,7 +266,7 @@ pub enum Msg {
     /// WebGL uses the GPU and we don't want to give untrusted content access to the GPU.)
     CreateWebGLPaintTask(Size2D<i32>,
                          GLContextAttributes,
-                         IpcSender<(IpcSender<CanvasMsg>, usize)>),
+                         IpcSender<Result<(IpcSender<CanvasMsg>, usize), String>>),
 }
 
 #[derive(Clone, Eq, PartialEq, Deserialize, Serialize)]
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 4dcd1705782..f02cd0d9524 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -64,20 +64,23 @@ impl WebGLRenderingContext {
                      canvas: &HTMLCanvasElement,
                      size: Size2D<i32>,
                      attrs: GLContextAttributes)
-                     -> Result<WebGLRenderingContext, &'static str> {
+                     -> Result<WebGLRenderingContext, String> {
         let (sender, receiver) = ipc::channel().unwrap();
         let constellation_chan = global.constellation_chan();
         constellation_chan.0
                           .send(ConstellationMsg::CreateWebGLPaintTask(size, attrs, sender))
                           .unwrap();
-        let (ipc_renderer, renderer_id) = receiver.recv().unwrap();
-        Ok(WebGLRenderingContext {
-            reflector_: Reflector::new(),
-            global: GlobalField::from_rooted(&global),
-            renderer_id: renderer_id,
-            ipc_renderer: ipc_renderer,
-            last_error: Cell::new(None),
-            canvas: JS::from_ref(canvas),
+        let result = receiver.recv().unwrap();
+
+        result.map(|(ipc_renderer, renderer_id)| {
+            WebGLRenderingContext {
+                reflector_: Reflector::new(),
+                global: GlobalField::from_rooted(&global),
+                renderer_id: renderer_id,
+                ipc_renderer: ipc_renderer,
+                last_error: Cell::new(None),
+                canvas: JS::from_ref(canvas),
+            }
         })
     }